eickman



Jan.,9, 1 d 0. yv. c. EICKMAN PAPER CLAMP- Origihl Filed March 26, 1955 4 Sheets-Sheet 1 7 5 m U, M

Jan. 9, 1940. w, c, E|CKMAN 1 2,186,136

PAPER CLAMP Original Filed March 26, 1955 4 Sheets-Sheet 2 Snventor,

W41. TEE c. E/CK/VA/Y attorney,

W. C. EICKMAN Jan. 9, 1940.

PAPER CLAMP Original Filed March 26, 1935 4 Sheets-Sheet s Snvcntor,

14 417277 C. E/(f/Vl/V Gttorncg Jan, 9, 1940. w, c E|KMAN 2,186,136

I PAPER CLAMP Original Filed March 26, 1935 4 Sheets-Sheet 4 6,' 4 3nventor Gttorneg Patented Jan. 9, 1940 UNiiE. "YATES PAPER,

CLAMP Walter C. Hickman, Dayton, Ohio, assignor to Harris- Seybold-Potter Company, Cleveland,

Ohio, a corporation of Delaware Application March 26,

1935, Serial No. 13,081

Renewed January 30, 1939 21 Claims.

This invention relates to paper cutting machines, and particularly to mechanism for clamping piles of paper to the cutting table of paper cutting machines while they are being out.

My clamping device is of the type that is self adjusting and operates automatically, clamping the paper with spring pressure before the knife reaches the paper in its descent and holding the paper until the knife has risen clear of it.

One of the objects of my invention is to co-m-' pensate for variations in the tension of the spring due to differences in the thickness of the piles. of paper, so that the clamping pressure imposed on the paper'is practically uniform, regardless of the thickness of the pile of paper. ,Another object is to perform the function of the mechanism .with a comparatively short and light spring.

I have developed my invention in three forms, in the first of which there is but a single toggle joint, while in each of the other two forms there are a plurality of toggle joints.

In the accompanying drawings:

Figure 1 is a side elevation of the first form of machine, showing the parts in normal or inactive position;

Figure 2 is a rear elevation of the machine, with the parts in the position shown inFigure 1;

Figure 3 shows the operating mechanism of the machine at the endof half its cycle;

Figure 4 is a side elevation of the second form of my invention, in which a plurality of toggle joints cooperate; I

Figure 5 is a rear elevation of the machine shown in Figure 4;

Figure 6 shows the position of the clamping mechanism shown in Figures 4 and 5 when the mechanism has moved one-half of its cycle and the machine contains a thick pile of paper;

Figure 7 shows a view similar to Figure 6, save that the pile of paper, not shown, is very thin;

Figure 8 is a rear elevational view of the third and preferred form of my invention, with the parts in their normal or home positions;

Figure 9 is a side elevational View of the structure shown in Figure 8, with the parts shown in their normal or home positions;

Figure 10 is a side elevational view of the structure shown in Figure 9, with the parts in the 50; positions they will occupy when a thin pile of paper is being cut, and

Figure 11 is a View similar to that shown in Figure9,except that the parts are in the posit on they will occupy when a thick pile of paper is being 6 cut. a

In Figures 8 to 11 inclusive, the frame and some of the parts of the machine are omitted.

Referring now to Figures 1 and 2, the frame of the machine comprises a back Ill, side irames H, base it and a bed plate or table l3. An opcrating shaft M is mountedto rotate in bearings formed in the frame members II, which shaft is rotated one revolution at a time by a gear wheel 55. The gear wheel i5 is rotated by a pinion l6, rigidly secured to a shaft ll, which shaft I! is driven by a motor, not shown, through a clutch, also not shown, of the kind commonly used in driving paper cutting machines. A knife l8, mounted on a frame 19, is moved down and up in guides 20, by means of pitmans 2i, only one of which is shown, operated by the crank 22 carried by 'the'shaft M. The clutch is so arranged that when the operator presses a small lever, not shown, the clutch is connected and made to rotate the shaft l4 one revolution, after which the clutch disconnects itself, leaving the shaft 14 in the position it occupies in Figure 1, that is, with the knife'lB elevated.

At 25' is shown a rock-shaft, at each end of which an arm-25 is rigidly secured. Above the table it a clamping member 21, mounted in suitable guides, is connected to the arms 26 by links 28. At 29 is shown a pile of paper in place on the table ready to be out. See Figure 2. It is to be understood that this pile of paper may be as high as can be conveniently placed under the clamping member 21, or it may be of any thickness less than that.-

Rigidly' secured to the rock-shaft 25, approximately 180 around from the armsZt, is an arm '39, to the end of which, at the point 3!, is connected the strut 32*of a toggle joint. This strut is in reality a pair'of links 32', one on each side of thearm 30. See Figures 2 and 3. For reasons of clearance, which will presently appear, one of these links 32 (right-hand link shown in Figure 2) is made curved. A strut 33, the lower end of which is pivotally secured at 34 between lugs 345 formed on the base I2, is connected at 35 to the inner ends of the links 32, forming the knee of the toggle joint. The term toggle joint as hereinafter used shall be interpreted in accordance with the following definition: Two rods or plates, hinged together, and employed to transmit a varying force by lateral pressure on the hinge, which is called the knuckle or knee. Pivotally connected to the inner end of the strut 33, near the knee 35, is the end of a threaded rod 3%. Thi-s rod passes transversely and freely through a short shaft 37, which shaft is mounted to rock in lugs formed on the back Ill. Confined between this shaft 31 and a nut 38 screwed on the rod 35 is a compression spring 39. The nut is in fact a wheel with a threaded hub. The rod 36 might be connected directly to the knee 35, and in effect it is so connected, but in order to make the average position of the rod more nearly horizontal this separate connection is provided, as at it. As will be readily seen, the spring 39 being a compression spring its tendency to expand in length tends to increase the distance between the shaft 3'! and the nut 38, and thereby draws the connection All? toward the shaft 31. In other words, the tension of the spring 39 tends to straighten the knee of the toggle joint, thereby moving the rockshaft clockwise, as it is seen in Figure 1, thus drawing the clamping member 27 down onto the pile of paper 25, and clamping the paper to the table it. This very thing has happened as the parts are shown in Figure 3.

That is, the pivotal points 3|, 34 and 35 of the toggle joint are more nearly in alignment in Figure 3 than in Figure 1, due to expansion of the spring 39.

, As is well known, the power of a spring diminishes as its tension decreases. Therefore the power or tension of the spring 39 is less in Figure 3 than it is in Figure 1. As is also well known, the power required to produce a given endwise pressure by means of a toggle joint becomes less and less as the struts of the toggle joint approach alignment with each other. It therefore follows that the decreasing power of the spring, as the clamping member 2'! approaches the table, is compensated for by the increas ng leverage of the toggle joint, as the struts approach alignment. In fact, the loss in spring power can, if desired, be more than compensated for by the toggle because the ratio of pressure obtained to the power expended increases as the struts approach alignment. It is not necessary to go into this, however. It sufiices to say, which can be demonstrated mathematically if necessary, that by means of the toggle joint, a spring having sufficient power to clamp the stack of paper with the parts in the position shown in Figure 1, can, by proper proportioning of the parts, be made to retain sufiicient power to produce at least as much clamping pressure with the parts in the position shown in Figure 3. Going a step farther it may be stated that the parts can be so designed that increased pressure is obtained when the pile of paper is high and reduced pressure when the pile is low, or the parts may be so designed that the contrary result is obtained.

I have already stated that Figure 1 shows the parts in their normal or home position. Figure 3 shows th parts in the position they occupy at the end of the first half of a cycle, that is, with the shaft i turned 189 from the position it occupies in Figure 1. An eccentric 45 is rigidly secured to the shaft it, which eccentric carries a strap l5. Extending from the strap 45 is a slotted arm All, which embraces a stud 48 that projects laterally from the arm 35. Obviously, when the shaft Ml, as shown in Figure 3, is rotated the remaining half of its cycle, that is to the position it occupies in Figure 1, the arm 41, through its connection with the stud 58, rocks the shaft 25 to the position it occupies in Figure 1. This crooks the knee 35 and compresses the spring It will be observed that in Figure 1 a line from the center of the eccentric to the center of the stud 43 will pass through the center of the shaft I l; in other words, the spring is held by the eccentric being on a dead center. Thus no latch or similar mechanism is required to sustain the spring tension, which is at its maximum when the machine is in its normal position. When the machine is operated, the eccentric moves its full stroke at each revolution of the shaft Hi. This permits the spring to move the clamping mechanism until the clamping member 21 become seated on the pile of paper that has previously been placed on the table. Thus it is seen that the clamping mechanism is operated by the spring. The parts. are so timed that the clamping member 21 seats itself on the pile of paper before the knife descends far enough to begin cutting the paper. On the second half of the cycle the knife rises above the paper before the end of the slot in the arm 41 reaches the stud 43, that is before the pressure of the clamping mechanism is removed from the pile of paper. Then the end of the slot in arm 41 engages the stud 58, the remainder of the stroke of the eccentric is used in tensioning the spring and raising the clamping member 2'! to the position it occupies in Figure 1.

I shall now describe the structure shown in Figures 4 to 7 inclusive. Referring principally to Figures 4 and 5, the frame of the machine comprises a front plate 5| side frames 5|, a base 52 and a table or bed plate 53. An operating shaft 54 carries and is driven by a gear wheel 55. A pinion 56 drives the gear 55 and a motor and clutch, not shown, drive the pinion. As before, the clutch is of the type commonly used on paper cutters. There is also a knife 58, mounted on a frame 58 in guides so, moved down and up by pitmans 6|, only one of which pitmans is shown, operated by a crank 62 carried by the shaft 54, as before. A rock-shaft 65 carries arms 66 which are connected to a clamping member 61 by links 58, all as before.

One end of a strut of a toggle joint is attached to 2. lug 78 formed on the frame of the machine. This strut consists of two links H, see Figure 5, which are connected to the lug 10 at 12. One end of the other strut 1'3 of the toggle is connected at M to the arm 15 of a lever 0f the first class, the fulcrum of which lever is pivotally connected at 16 between lugs I1 formed on the base of the frame. .The struts II and '13 are joined at 18, the strut 13 being bifurcated to embrace the ends of the links which constitute the strut H. The joint it constitutes the knee of the toggle, and the rod that serves as the joint 18 passes transversely through the enlarged end of a guide rod 19. The guide rod '19 extends perpendicularly to the toggle, and its outer end is adapted to slide in a bushing 81!, which bushing in turn is screwed into an arm 8i extending upward from the base of the machine frame. Confined between the head 82 of this bushing and a flange 83 on the other end of the rod, near the knee, is a compression spring 8:3, the tension of which spring tends to straighten the knee of the toggle. The tension of-the spring is adjustable by screwing the bushing 8!) one way or the other in the arm 8| and looking it with the jamb nut 85.

Rigidly secured to the shaft 54 is an eccentric 99, carrying an eccentric strap 9|, having a wing 92 extending toward the left as seen in Figure 4. A pair of links 93 connect this wing 92 to the end of an arm 94 that is rigidly secured to the rock-shaft 180 around from the arms 65. A bifurcated link 95 embraces the wing 92 and links 83, its lower end being connected to the endof an arm 56. See Figure 5. This arm 96 is the ment of the pivot ltil along the arc EM.

second arm of the lever of the first class, previously referred to, of which the first arm is 15, arranged to rock on the fixed fulcrum 16.

I shall now explain the operation of the machine just described beginning with the parts in the position they occupy in Figure 4, which is the normal or home position, the clamping menu ber 6? being then at its highest point. It is held so by the spring 8 5, the spring being under a certain amount of tension, which I shall-refer to as initial tension. This tension presses the knee 73 toward the right, which presses the joint M down on the pad I03, this in turn holding the lever 15-436 and the pivot I02 stationary. Rotating the shaft 54 one-half of .a revolution, which is one-half of its cycle, will produce one of sev eral conditions, according to how much paper may have been put under the clamping member 5?. If a high pile of paper has been put under the clamping member Ei'l, so that said member cannot descend far, the parts will ultimately assume a position somewhat like that illustrated in Figure 6. That is, referring again to Figure 4, the eccentric strap 9|, including the wing 92 and pivot we, will first move bodily to the left. As the pivot I92 is still held stationary by the initial tension of the spring 84, the link 95 will swing on the pivot H32 and the pivot H36 will move on the arc I04, see Figure l. Meanwhile the upper end of link 33 will be rotating the shaft '55 through the pivot it! and the arm Q 5, and through the arms 65 and links 83 (Figure 5) the shaft 65 will pull the clamping member 61 down on the pile of paper, thus arresting the move- But with the bodily movement of the eccentric strap 9i still continuing to the left, the link. 5'3 now begins to swing to the left on the pivot ill I, which pivot has now become stationary, causing the pivot 2% to move to the left on the are its, Figure 6. j

I At this point begins an increase in the tension of spring 85%, and it is done in this way: It will be noticed that the general direction of the arc Hi5, Figures 6 and 7, is slightly downward, and that continued bodily leftward movement of the eccentric fil will cause the pivot N30 to move the link 35 downward. This will cause the link to rock the bell-crank lever ill-95 counter-cloclnyise on its axis it, thereby raising the joint it off of the pad i 83. This puts more bend in the knee of toggle 12-13 and by moving knee it to the left, as seen in Figure 4, compresses the spring 84 further, thereby increasing the tension of the spring.

At first thought it would seem that this increase in the tension of spring at would increase the pressure of the clamping member ti on the pile of paper, but remembering that as the bend in the knee #8 increases, the power of the toggle lil'3 or its mechanical advantage, so to speak, decreases, the increased power of the spring is practically offset by the decreased power of the toggle. At the same time an equalization is taking place between the toggle formed by struts and 6 and the toggle 9'3 t5. These equalizations are more or less complete according to the design of the toggles, and in any event the pressure of the clamping member on the pile of paper is maintained practically uniform, regardless of the thickness of the pile of paper under the member This illustrated Figures 6 7, which will be further explained presently. It will be seen that in. effect the clamping member 6". is positively moved down to the pile of paper by the shaft 54, up to the time the member 6"! comes to rest on the pile of paper; that is, only while the center tilt is held in a stationary position by the spring 84. In other words, it might as well be stationary in fact, up to the time the member 5? is stopped by the pil of paper. After this, however, the movement of the shaft ti l continuing, yielding oi the spring 84 and counter-clockwise movement of the lever F5-% is necessary to keep from breaking something. That is, the spring t i serves two functions after the clamping member ill comes to rest on the pile of paper: first, it acts as a. relief to allow continued leftward movement of the eccentric Q5, and second, it supplies the tension whereby the clamping member 6? holds the stack of paper while it is being cut.

To sum up the matter, the thickness of thepile of paper may vary from a very thin pile to a pile that taxes the capacity of the machine. But a spring tension of a given equal amount will answer the purpose in both cases, and in any intermediate case. It happens that a tension suflicient for holding the paper for cutting purposes is also suillcient for holding the center 5532 stationary. Therefore, the initial tension of the spring as is obtained by compressing the spring able amount of pressure tending to hold the joint it to the pad Hi3, and holding the center it? immovable. Referring to Figure which it will be recalled depicts a case wherein a thick pile of paper has been placed on the table, resulting in the clamping member 6'? having moved but a short distance, it will be seen that the spring 8 4 has been compressed a considerable amount, and compare this with Figure .7, where a thin pile of paper is under the clamping member til, it will be seen how much less the spring becomes compressed when a thin pile is being operated upon. Comparing Figures 6 and 7 also shows that the equalization which is produced by the combination of toggles, previously described, results in the pressure being substantially the same, whether a thick pile or a thin pile of paper is placed under the clamping member 6's.

I shall now describe the third version of my invention; or rather what may best be described as a modified form of the double toggle mechanism just described. In this construction as the other two, there are drivingparts and connections, not shown, which operate a main shaft, in this case shaft ltd, whereon is secured an cccentric ibl, encircled by eccentric strap I52, which strap is connected to the knee 1153 of a toggle joint 154455; The lower strut of this toggle comprises two links, l see Figure 8, the free ends of which p-ivotally joined to an a m 556 which to a rock-shaft it? The r strut of the toggle comprises twolinks the-iii upper ends of whicl'i pivotally connected, to a arr-3 559, this arm being keyed to a rock-shait ill The rock-shaft corresponds to rock of the structure shown in Figi to Z.

1e shaft i5'l is mounted to rock in a pair mounted upon the base of the machine. Keyed to this shaft are a pair of arms I5I, which arms are in effect one arm and extend from the shaft in a direction substantially opposite to the direction in which the arm i56 extends. Between the free ends of the arms 56! a link I52 is pivotally attached at 52 which link forms one strut of another toggle joint. The other strut of this toggle consists of two links, I53, one on each side of the knee Hi l of this last mentioned toggle joint. The upper ends of the links 563 are pivotally connected at ifit to the outer end of an arm I65 which is mounted to rock freely on the shaft I55. Between the knee end of the strut Hi2 and the adjacent end of each strut l53 are the eyes of two threaded rods I56, the whole being united by a single pivot rod Hi4, which forms the knee of this toggle l62 l53.

Each of the pillow blocks "it has an upwardly, diagonally extending arm Hill, each of which arms terminates in a notch or open bearing 568. Between the arms i5! is placed a U-shape frame, its, the bottom of which is provided with two holes that slip freely over the tension rods I58. Each of the arms of this U-shape frame is provided with a trunnion l'lfi, which trunnions rest in the bearings 558 and in which the frame 559 is adapted to rock. Compression springs I ll surrounding the tension rods I 55 are confined between the nuts W2 and the bottom of the U- shape frame 559. The upper ends of the strutlinks 253 are pivotally connected to an arm I55, which arm extends laterally from one end of a sleeve H5. This sleeve is arranged to rock freely on shaft E58. On the other end of the sleeve, extending laterally and substantially 180 from the arm I55, is another arm 9'56. Arms I65 and H6 are integral with the sleeve H5, and the three parts form in effect a lever adapted to rock on the shaft i523. Pivotally connected to the end of the arm H6 is one end of a link I'll, the lower end of which link is pivotally connected to the joint 5'18. The joint idl connecting the arms l6! to link N32, is adapted to rest on pads we, formed on the base of the machine.

Keyed to the shaft I158, near each end, is an lilo (only one is shown), and pivotally connected to each of these arms is an upwardly extending link iili. These correspond to arms 25 and links 128, of Figures 1 and 2, which carry the clamping member 21 of these figures. These arms 5% and links ISI also correspond to arms and links 63, respectively, of Figures 4 and 5. The clamping member, not shown, is adapted to clamp piles of paper of various thicknesses to a cutting table, also not shown, to be cut.

I shall now explain the operation of this structure, assuming that a pile of paper has been placed the cutting table, and that mechanism for rotating the shaft l5il one revolution, which mechanism is not shown, has been started. I shall also assume that an initial tension has been imparted to the springs I'll with the nuts I72. Remembering that the springs ilI are confined between the bottom of the U-shape member I69 the nuts Hi2, that the nuts are screwed on the tension rods E55, which rods are anchored in the knee rod lfi l, and that the trunnions ill] on the member 569 lie in the bearings I58, which bearings are immovable, it is plain that the spring tension is expended in pulling the knee H5 3 to the left as seen in Figure 9, and tending to straighten the toggle IliZ-Aiit. This results in the joint It? resting on the pad H9, which in turn holds the pivot I78 stationary. All of this action is similar to that of lever I596 and joint I02 of Figure l. Rotation of the shaft I moves the eccentric strap E52 bodily to the left, as seen in Figure 9. The strut I54 swings to the left on the center H8, causing the strut E55 to rock theshaft I58 through the arm I59 and center I19, and as will be understood rocking of the shaft I58 will move the clamping member down to the pile of paper through the links I 8! and the arms I80. When the clamping member comes to rest .on the pile of paper, the eccentric strap continuing to move to the left, the shaft l5? will be rocked counter-clockwise by the strut I54 through center I'll; and arm I 55. All of this action is similar to that which has been described in connection with Figure 4.

From now on the springs il'l serve as a relief, to permit the continued bodily leftward movement of the eccentric strap 52, this being necessary because the clamping member is now resting on the pile of paper and as a consequence the center Hi3 has become immovable. Continued leftward movement of the eccentric strap now moves the arm 555 downward, with consequent counter-clockwise movement of the shaft I57. The arm ifil being keyed to shaft I57, it follows that as arm i55 moves downward, arm I6! moves upward. Simultaneously with downward movement of the arm 555, the link Il'1, which is connected by joint 578 to arm I56, is pulled downward, this in turn rocking the arms I15 and I counter-clockwise, the arm I55 in turn raising the strut 563. The arm I65 is preferably made a little shorter than the arm I15 because the pres sure at l63= should be greater than at H6 in order to produce the proper final resultant pressure on the paper clamp through the links IBI, etc. In this connection it will be understood that the amount of effective movement imparted to the ivot sea is greater than the amount of effective movement imparted to pivot I63 resulting in increased compression of springs III, as I shall now explain.

The effective radial lengths of arms I16, I56 and substantially the some, while the effective radial length of arm 65 is less. This is due to the fact that an extended line I90, drawn through the centers of pivots I65 and I 64, crosses a line EQi, radial to center I58, at a distance from center shorter than the effective radial length of l'li-i, and 569. Therefore, when the center 262 lifts strut H52, as a consequence of center ilB being pushed downward by strut I54. strut N53 is prevented by the arm I55 from as great a distance as strut I 62 tends to it. This is because the efiective radial length of arm I55 is less than the effective radial length of 335. As struts i532 and 563 are connected by the knee this excess movement, of strut it?! results in increasing the bend in the knee of the toggle i""i63 The tension rods 5 5 being 1" in the knee I54, it is plain that increasing the bend in the knee HE draws the rods it to the right as they are seen in Figures 9. l0 and il, and since the springs iii! are confined between the nuts H2 and the U-shape frame 69. which frame is stationary, it is plain that increasing the bend in the knee I54 increases the compression in the springs.

Thus it is seen that this third Version of my invention produces the same results that the second version produces. I shall now show that it produces an additional useful result. namely, means whereby the springs may be shorter, thereby taking up less room. .It will be recalled that spring takes place where a thin pile of paper is being acted upon, and it is obvious that the spring must be long enough to permit the necessary amount of spring compression which a very thin pile of paper will involve, without injury to the spring.

' With the spring arrangement shown in Figures 8 to 11 the springs can be very short. This is be cause the amount of compression imparted to the springs can be varied. by varying ,the'eifective radial length of arm I65 with reference to the effective radial length of arm. 9E1. That is, leavng the effective radial length of arm l ii as it is.

the compression imparted to the springs will be increased by shortening the effective radial length of arm N55, or it will be decreased by increasing the effective radial length of this arm $65. For instance, if the effective length of arm I65 were increased so it equalled the effective length of.

arm 16f, no spring compression would be eifected when the lever Hit-46! rocked counter-clockwise,

On the other hand, the shorter the effective length of arm I65 is, the greater will be the contraction of the springs, until a condition. is reached such as is found in Figure 4, where the upper-end of the strut H, which corresponds to strut S53, is anchored on the stationary center '12. In this form of my invention I have found that l is preferable to make the lateral movement of the knee i 3, or in other words the lineal amount that the springs I?! are compressed, se t between one inch and two and one-ha: inches because the operating efiiciency of the springs in a mechanism so designed will then be approxi mately constant.

While Ihave described what seems now to be the preferred embodiment of my invention, it is conceivable that various modifications in the configuration, composition and disposition of the component elements going to make up my invention a whole, as well as in the selective combination and application of the respective elements, may occur to those skilled in the art, and no limitation is intended by the phraseology of the foregoing description or illustrations in the accompanying drawings.

What is claimed is:

1. In a paper cutting machine, a movable clamping member, a toggle joint, one strut whereof is pivoted at a fixed point, the other strut being connected to one end of a lever of the first class. a rock-shaft carrying a rigidly attached arm, a pair of links connecting the end of said arm to the other end of said lever, an operating shaft carrying an eccentric, the strap whereof is connected to a joint whereby said links are connected, a second arm rigidly secured to said rockshaft and operably connected to said clamping member, and a spring, one end of which is anchored to a fixed point, the other end being attached to the knee of said toggle in such a manner that the stress of the spring tends to straighten the knee.

2. In a paper cutting machine, a member adapted to descend upon a pile of paper placed in a machine to be cut, an operating member, means whereby when the operating member is operated it causes the clamping member to descend and bear upon the paper with a resilient pressure sufficient to clamp it whenit is being out, said means comprising two toggle mechanisms the angularity of one of. which decreases as the angularity of the other increases to maintain substantially constant the resilient pressure, aforesaid. 3 In a paper cutting .machine, a movable clamping member, a toggle joint, one strut of which is connected to a fixed point, the other strut being connected to said clamping member, a spring, one end whereof is anchored to a fixed point, the other end being connected to the knee of the toggle joint, a shaft which moves one revolution at each cycle of the'machine, means whereby during the last half of its revolution said shaft increases the bend in said knee, thereby stressing the spring, and retires the clamping member, a paper knife moved by said shaft during the first half of its cycle to cut the paper held by said clamping member, the concurrent movement of the shaft allowing the spring to operate the clamping member to clamp the paper before the knife reaches the paper. I

4. In a paper cutting machine, a toggle joint, one strut whereof is connected to a fixed point, the-other strut being connected to an arm rigidly secured to a rock-shaft, a spring, one end of which is anchored to a fixed point, the other end being connected to the knee of the toggle joint so its stress will tend to straighten the knee; a second arm secured to said rock-shaft, a movable clamping member and connecting means between said member and said second arm, an operating shaft which moves one revolution during each cycle of the machine, an eccentric mounted thereon, the strap whereof is connected to the first mentioned arm in such a way that during the latter half of the cycle of the operating shaft the rock-shaft is moved to crook the toggle-joint, stressthe spring and retire the clamping memher.

5. A paper cutting machine comprising, a knife movable through a relatively long stroke to cut stacks of paper of varying heights, a paper clamping member movable in unison with but ahead of said knife to clamp said stacks of paper, operating means for said knife and said clamping member, linkage. positively connecting said operating means and said knife, linkage connecting said operating means and said clamping member, the second said linkage comprising a resilient member adapted to yield and .permit said clamping member to be arrested in its stroke when it has come in contact with a stack of paper and a predetermined pressure thereon has been reached, and means including a portion of the second said linkage for diminishing the leverage through which the force of the resilient member is applied operating shaft, eccentric means on said shaft, a

knife and clamp operating member operable by said eccentric means, a toggle joint having its knee connected to said operating member, a second toggle joint, a spring having one end connectedto a fixed point and the other end connect ed to the knee of the second toggle joint, a lever rockable midway of its ends on a fixed f ulcrum, one free end of the lever being connected to a free end of the first toggle joint and the other free end of the lever being connected to a free end of the second toggle joint, a hinge connecting the other free end of the second toggle joint to a fixed point, clamp operating linkage connected to said clamp, and means connecting the other free end of the first toggle joint to said clamp operating linkage.

7. In a paper clamping mechanism for paper cutters, a paper clamp, a toggle joint one end of which is operatively connected with said clamp, a support for the opposite end of the toggle joint, a spring arranged when stressed to exert pressure on the knee of the toggle and thereby to cause the clamp to grip a pile of paper, the spring being otherwise so mounted and arranged as to decrease the stress of the spring as the toggle joint straightens and to increase the stress of the spring as the included angle of the toggle joint contracts.

8. In a paper clamping mechanism for paper cutters, a paper clamp, a toggle joint one end of which is operatively connected with said clamp, a fixed pivot for the opposite end of the toggle joint, and a spring arranged when stressed to exert pressure on the knee of the toggle joint, the spring being otherwise so mounted and arranged as to increase the stress thereof as the included angle of the toggle joint contracts.

9. In a paper clamping mechanism for paper cutters, a clamp, two levers of the first class, parallel spaced pivots for said levers, a link connecting one end of one lever to the corresponding end of the other lever, a toggle joint connected at its ends to the remaining ends of the two levers, a spring connected with the knee of said toggle joint, means operatively connecting said clamp to one of said levers, and means for rocking one of said levers to apply said clamp, one strut of the toggle joint being connected to its lever on a shorter radius than the other strut, said spring being so mounted and arranged as to increase the stress thereof as the included angle of the toggle contracts.

10. In a paper clamping mechanism for paper cutters, a clamp, first and second toggle joints, a lever of the first class to the opposite ends of which one end of each of the said toggle joints is connected, a pivotal support for the opposite end of the first toggle, the opposite end of the second toggle being operatively connected with said clamp, means for applying power to the knee of the second toggle for straightening said toggle and applying said clamp and for bending the first toggle, and spring means connected with the knee of the first toggle opposing the bending thereof.

11. In a paper clamping mechanism for paper cutters, a clamp, first and second toggle joints, a lever of the first class to the opposite ends of which one end of each of the said toggle joints is connected, a pivotal support for the opposite end of the first toggle, the opposite end of the second toggle being operatively connected with said clamp, means for applying power to the knee of the second toggle for straightening said toggle and applying said clamp and for bending the first toggle, spring means connected with the knee of the first toggle opposing the bending thereof, and means for connecting the said pivotal support for the first toggle with the said lever of the first class to move proportionately with the movements of that lever.

12. In a paper cutter having a crank shaft, a paper knife and a paper clamp arranged to stop at upper dead center of their strokes, the combination of actuating means for depressing said clamp, a spring for operating said actuating means, and crank means on said crank shaft for moving said actuating mechanism in opposition to said spring to raise said clamp, said crank means being arranged to reach dead center position when said clamp is in upper dead center position.

13. In a machine of the class described, a paper knife, a paper clamp, a toggle joint mounted at one end upon a fixed pivot and operatively connected to said paper clamp at the other end, a spring operatively connected to the knee of said toggle tending to straighten the toggle, a shaft which makes one revolution for each cycle of the machine, means operatively associated with said shaft and effective during the first half of said cycle for moving said knife to effect the cutting operation, and means operatively connected with the shaft and effective during the second half of its revolution for putting the spring under stress.

14. In a machine of the class described, a paper knife, a paper clamp, a toggle joint mounted at one end upon a fixed pivot and operatively connected to said paper clamp at the other end, a spring operatively connected to the knee of said toggle tending to straighten the toggle, a shaft which makes one revolution for each cycle of the machine, means operatively associated with said shaft and effective during the first half of said cycle for moving said knife to effect the cutting operation, and means operatively connected with the shaft and effective during the second half of its revolution for putting the spring under stress and raising the clamp.

15. In a machine of the class described, a paper knife, a paper clamp, a toggle joint mounted at one end upon a fixed pivot and operatively connected to said paper clamp at the other end, a spring operatively connected to the knee of said toggle tending to straighten the toggle, a shaft which makes one revolution for each cycle of the machine, means operatively associated with said shaft and effective during the first half of said cycle for moving said knife to effect the cutting operation, and means operatively connected with the shaft and effective during the second half of its revolution for bending the toggle to decrease the included angle between its struts and for putting the spring under stress and raising the clamp.

16. In a machine of the class described, a paper knife, a paper clamp, a toggle joint mounted at one end upon a fixed pivot and operatively connected at its opposite end to said paper clamp, a spring operatively connected to the knee of said toggle tending to straighten the toggle, an operating mechanism, means energized by said spring and effective during the first half of the cycle of the machine for moving said paper clamp into clamping position and maintaining it there during the descent of the knife, said operating mechanim also comprising means effective during the last half of the cycle for bending the toggle, thereby stressing the spring, and raising the clamp to inoperative position.

1'7. In a paper cutting machine, a clamping member and a cutting knife operable through relatively long strokes for holding and cutting stacks of paper of varying heights, a resilient means under stress urging said clamping member toward a stack of paper, means restraining said resilient means from moving said clamping means toward said stack of paper, means for operating said knife, means operative ahead of said knife for releasing said restraining means thereby permitting said resilient means to move said clamping means upon said stack of paper,

said resilient clamp operating means comprising 75 chine and the free end of the other leg secured a toggle joint to. the knee of which saidspring is connected, said toggle joint constituting. come pensating linkage for applying substantially the same pressure tosaid clamping means whether said resilient means is in a fully stressed or a partly. stressed state 18. In a machine of the character described, a clamping member operable through a-relatively long, stroke to reach andclamp stacks of paper when said clampingmember encounters a stack of paper during its'strokeand the operating member continues its stroke, and leverage means comprising a toggle joint between said operatingmember and said clamping member connectedto the spring at the knee of the toggle, whereby as the force of said spring-increases-the leverage decreases and the pressureon said stack remains substantially constant throughout the stroke.

19. In a paper cutting machine of the character described,v a clamping member, a lever fulcrumed intermediate its ends on the frame of.

themachine and having one end connected ,to the clamping member, a second lever fulcrumed intermediate its ends on the frame of the machine, a toggle joint having the free end of one leg secured to the free end of the first lever and- .the free end of the other leg secured to one end of the second lever, operating means attached to the knee of the toggle joint to straighten the legs of the joint for applying the clamping end of one leg hinged to the'frame of the mato the other'end of the second lever, and a spring under initial stress acting. against the knee of the second toggle joint tending to straighten,

that toggle. v

20, In apaper clamping mechanism of the character described, a paper clamp, a spring, an operating means, leverage means differentially connecting said operating means to said clamp and said springjwhereby the force of said operating means is divided between said clamp and said spring, said leverage means comprising a toggle to the knee of whichsaid spring is connected and being such that when said spring gradually yields and becomes shorter and stronger, the pivotal points of thelevers shift gradually to cause a progressivelygreater proportion of the applied forceof the operating means to bear on I the spring and less proportion on the'clamp,

' whereby the force applied to the clamp remains substantially the same at any stage of the stress of the spring. 7

21. In a paper cutting machine, a knife, a movable clamping member, a toggle joint, one strut whereof is. pivoted at a [fixed point, the

other strut being connected to move said clamping member, a spring, one endof which is .anchored to a fixed point, the other end being connected to the knee of the toggle joint, means eifective during the down stroke of the. knife permitting the spring stress to straighten the knee of the toggle joint and move-said clamping member to clamp a pile of paper,and means for bending the toggle and putting the spring under stressduring the up stroke of theknife. member, a second toggle joint having. the free,

" WALTER c. EICKM-AN. 

